Stable petroleum product



Patented Apr. 30, 1940* STABLE PETROLEUM PRODUCT Clarence M. Loane andBernard H. Shoemaker,

Hammond, Indi, assignors to Standard Oil Company, Chicago, 111., acorporation of Indiana No Drawing. Application December 13, 1937,

. Serial No. 179,473

7 Claims. (o1. 1964.149)

This invention relates to stable petroleum products and in particularoxidation stable white mineral oils and products containing the same.

White mineral oils, often also referred to as mineral medicinal oils andliquid paraffins, are usually prepared by treating petroleum distillatesof the desired viscosity with fumingsulfuric acid, the amount of acidused ranging from about 2 lbs. to about 8 lbs. of acid per gallon ofoil. White oils which will pass the U. S. Pharmacopoeia acid test(hereinafter referred to as U.'S.P. acid test) may be prepared bytreating a distillate stock of about 100 seconds to about 800 secondsSaybolt viscosity at 100 F. with from about-' lbs. to about 8 lbs. of104%; sulfuric acid per gallon of oil in /2 lb. dumps, neutralizing theacid treated oil with a neutralizing agent such as caustic, washing theneutralized oil with about volumes of 50-55% alcohol per 100volumes ofoil and treating the neutralized oil with an absorbent material such asclay. Mineral medicinal oil so treated will give a color not greaterthan 3 N. 'P. A. by the U. S. P. .acid test which consistsof heating 5cc. of oil and 5 cc. of chemically pure sulfuric acid in a glassstoppered cylinder for ten minutes in a water bath and shaking at secondintervals. The oil must remain colorless and'the acid must not becomedarker than pale amber (almost 3 N. P. A.)

In additionto the mineral medicinal oils other grades of white oils aremade which, because of their use, need not pass the U. S. P. acid test.These oils are referred to as technical white oils or commercial whiteoils and are obtained by treating petroleum distillates of thedesiredviscosity range with from about 2 lbs. to about 5 lbs. of fumingsulfuric acid per gallon of oil and neutralizing and washing theneutralized oil with alcohol as in the treatment of U. S. P. white oilsabove described. White mineral oils which have been so treated that theywill not pass the U. S. P. acid test will hereinafter be referred to astechnical white oils.

It is the primary object of the present inventionto provide whitemineral oils which are highly resistant to oxidation. It is anotherobject of the present invention to provide a technical white oil whichis highly resistant to oxidation and which when added in small amountsto other substances will render them resistant to oxida-' tion.

We have found that technical white oils having a sulfur content of fromabout 0.01% to about 0.1% processed from certain crudes, in particularhigh sulfur crudes having a sulfur content of white oil containing notechnical white oil from about 0.5% to about 2.5%, are resistant tooxidation to a degree heretofore unknown and unexpected. Whereas theordinary technical white oils have an averageRogers stability life test1 (hereinafter described) "of about 40 hours, we 5 have found that thetechnical white oils processed from high sulfur crudes in the mannerherein described have Rogers stability life tests of about 500 hours tomore than 3600 hours.

Exemplary of our invention butnot limitative thereof, a distillateobtained from Winkler crude oil, which crude oil has a sulfur content ofabout 1.5%, when treated with about 5 lbs. of 104 sulfuric acid to givea technical white oil of about 30+ Saybolt color and a Saybolt viscosityof about '75 seconds at F. and a sulfur content of from about 0.02% toabout 0.04%, has 2. Rogers stability life in excess of 3640 hours. TheRogers stability life test (as described in detail in Ind. 8;

Eng. Chem., vol. 19, page 308, 1927) is an index of the oxidationresistance of the oil. The average Rogers stability life (time todevelop an acidity equivalent to 1 mg. KOI-I per gram of oil) of theordinary technical white oil is about 40 hours.

- Wehave found that U. S. P'. white oils can be made highly resistant tooxidation by the addition of from about 0.05% to about 5% of a technicalwhite oil which will not pass the U. S. P. acid test and particularlytechnical white oils from high sulfur crudes. The oxidation stability ofU. S. P. white oils containing up to about 2% of a technical white oilfrom a high sulfur crude isabout 7500% greater than the same U. S. P.

a high sulfur crude. v 1

We have found that up to about 2% of these technical white oils fromhigh sulfur'crudes may be added to U. S. P. white oils and still enablethe white oils to pass a U. S. P. acid test. The effect of up to 2% oftechnical white'oil from high sulfur crude on the U. S. P. acid test isillustrated by the following table.

Table 1 '45 To. s. P. acid test-N. P. A.

colors Oil

